Field of the Invention
The present invention relates to apparatus, systems and methods for enabling access to data, and in particular to enabling access to data by a plurality of requesting parties.
Description of the Related Technology
In many communications systems it is desirable to control access to data. In particular it is desirable to have a system in which different requesting parties are allowed to access certain data portions within a given block of data while being prevented from accessing other data portions. Moreover, it is desirable to allow different parties access to the same data portions of data, while not, for example, giving two parties access to all the same data portions; that is, parties are allowed overlapping, but not necessarily identical, access.
One example of a system to provide this is described in US 2005/0180573. In this example a block of data is divided into portions. Each portion of the data is then encrypted using a different portion specific key. Requesting parties are then provided with a party specific key, which can be used to derive or decrypt portion specific keys. The party specific keys are arranged such that a given party is only able to acquire portion specific keys corresponding to portions of the data to which the party is allowed access. This enables a requesting party to decrypt, and thus access, the portions of the data to which that party is allowed access.
However, this system comes with a number of drawbacks. For example, a lost key, or removal of access rights of a given requesting party, means that all portions of the data to which a given party was previously allowed access have to be re-encrypted. In addition, this system requires any computerized equipment used by the parties to be capable of decrypting the data adding overheads to the overall system.
Consequently, there is a need for an improved system for enabling access to data.